hydrocarbon nomenclature
TRANSCRIPT
Naming Hydrocarbons (nomenclature)
Drawing Structures: It’s All Good
CH3
CH
CH
CH3
CH3
CH3
CH3
CHCH
CH3
2-butene
This is called the “condensed structure”
C C C C
H
H
H
H H H
H
H
CH3 CH CH CH3
On a test, choose a method that shows all HsCH3CH=CHCH3
Using brackets can also shorten some formulas: CH3CH2CH2CH2CH2CH3 vs. CH3(CH2)4CH3
Basic Naming of HydrocarbonsHydrocarbon names are based on: 1) type,
2) # of carbons, 3) side chain type and position 1) name will end in -ane, -ene, or -yne2) the number of carbons is given by a “prefix”
1 meth- 2 eth- 3 prop- 4 but- 5 pent- 6 hex- 7 hept- 8 oct- 9 non- 10 dec-
Actually, all end in a, but a is dropped when next to a vowel. E.g. a 6 C alkene is hexene
Q - What names would be given to these:7C, 9C alkane2C, 4C alkyne1C, 3C alkene
heptane, nonaneethyne, butynemethene, propene
Mnemonic for First Four Prefixes
First four prefixes• Meth-
• Eth-
• Prop-
• But-
Monkeys
Eat
Peeled
Bananas
Decade
Decimal
Decathalon
Other Prefixes
• Pent-
• Oct-
• Dec-
• Hex-, Hept-, Non-
Quiz – On LL (5 min.; 12 pts)
1. What are the 3 classes of hydrocarbons, based on number of carbon-carbon bonds?
2. Give the 10 organic homologous prefixes, in order, from 1-10.
3. Name these compounds:
CH3CH
CH
CH3
CH3 CH3
C2H4
Numbering CarbonsQ- draw 1-penteneA- Where’s the double
bond? We # C atoms.
• Naming compounds with multiple bonds is more complex than previously indicated.
• When 2+ possibilities exist, #s are needed.• Always give double bond the lowest number.• Q - Name these
C C C CCH3
H
H
H
H H H
HCH31
C2
C3
C4
C5
H
H
H
H H H
HCH35
C4
C3
C2
C1
H
H
H
H H H
H
1-pentene
C CCC
CC CH3 H3
H H H H H
HHH
C C C
H
H
H H
Quiz (LL, 3 min.)
1. Name the 4 groups of hydrocarbons (alphabetically)
2. Draw the structures for the following compounds:
A. 2-octeneB. 4-decyneC. hexaneD. 3, 4, 5 – triethyldecaneE. 2-chloro – 4 – methyl – nonane3. When done, take homework out to review!
Homework: Section Review 25.3 and 25.4 (notebook, show all work); read p. 762-765; both on quiz tomorrow!
CH3 CH3
CH3
CH3Naming Side Chains• The names of molecules with
branches are based on: side chains, root
• The “root” or “parent chain” is usually the longest possible hydrocarbon chain.
• The root must include multiple bonds if they are present. If a cyclic structure is present it will be the root even if it is not the longest chain.
• Side chains are also called “side branches” or “alkyl groups”. Their names end in -yl.
Common side chains :-CH3 methyl, -CH2CH3 ethyl, -CH2CH2CH3 propyl
2,3-dimethylpentane
CH3 CH3
CH3
CH3
IUPAC Rules for Naming Hydrocarbons1. Choose the correct ending: -ane, -ene, or -yne2. Determine the longest carbon chain. Where a
double or triple bond is present, choose the longest chain that includes this bond. If there is a cyclic structure present, the longest chain starts and stops within the cyclic structure.
3. Assign numbers to each C of the parent chain. For alkenes and alkynes the first carbon of the multiple bond should have the smallest number. For alkanes the first branch (or first point of difference) should have the lowest #. Carbons in a multiple bond must be numbered consecutively.
4. Attach a prefix that corresponds to the number of carbons in the parent chain. Add cyclo- to the prefix if it is a cyclic structure.
5. Determine the correct name for each branch (“alkyl” groups include methyl, ethyl, propyl, etc.)
6. Attach the name of the branches alphabetically, along with their carbon position, to the front of the parent chain name. Separate numbers from letters with hyphens (e.g. 4-ethyl-2-methyldecane)
7. When two or more branches are identical, use prefixes (di-, tri-, etc.) (e.g. 2,4-dimethylhexane). Numbers are separated with commas. Prefixes are ignored when determining alphabetical order. (e.g. 2,3,5-trimethyl-4-propylheptane)
8. When identical groups are on the same carbon, repeat the number of this carbon in the name. (e.g. 2,2-dimethylhexane)
IUPAC Rules for Naming Hydrocarbons
ene
Naming Side ChainsExample: use the rules on this handout to
name the following structure
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
Rule 1: choose the correct ending
ene
Rule 2: determine the longest carbon chain
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
Naming Side Chains
Rule 3: Assign numbers to each carbon
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
ene
Naming Side Chains
Rule 3: Assign numbers to each carbon
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
ene
Naming Side Chains
1-hexene ene
Rule 4: attach prefix (according to # of Cs)
Naming Side Chains
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
Rule 5: Determine name for side chains
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
1-hexene 1-hexene
ethyl
methyl
methyl
Naming Side Chains
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
1-hexene2-ethyl-4-methyl-4-methyl-1-hexene
ethyl
methyl
methylRule 6: attach name of branches alphabetically
Naming Side Chains
Rule 7,8: group similar branches
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
1-hexene2-ethyl-4-methyl-4-methyl-1-hexene
ethyl
methyl
methyl
Naming Side Chains
Rule 7,8: group similar branches
CH3 CH2 C
CH2
CH2 C
CH2
CH3
CH3
CH3
CH3 CH2 C2
CH21
CH23
C4
CH25
CH3
CH3
CH36
2-ethyl-4,4-dimethyl-1-hexene
ethyl
methyl
methyl
Naming Side Chains
2-butene
propene
1-butyne
CH3 CH CH2
CH3 CH CH CH3
CH3 CH CH C
CH3 CH3
CH3
2,4-dimethyl-2-pentene
CH C CH2 CH3
b) same
c) 5-ethyl-4-methyl-2-heptyne
a) 3,3-dimethyl-1-pentene
CH2 CH C CH2 CH3
CH3
CH3
CH3 C CH CH2
CH3
CH2 CH3
CH CH CH2
CH2 CH3
CC
CH3CH3
CH3
For more lessons, visit www.chalkbored.com
Quiz – 12 points (LL, 5 min.)We will be correcting this together.
Draw
• 3 – methyl-1,3-cyclopentene
• 2-ethyl-1-pentene
Name:
3.
4.
5.
Give both names!
Homework: Concept Practice #28-43, in
notebook (p. 768; show all work!)
IsomersSame molecular formula, different molecular structures.
Two types: structural and geometric isomers.
1. Structural Isomers: molecules with same chemical formula, but different molecular structures.
butane (C4H10) 2 – methylpropane (C4H10)
CH3-CH2-CH2-CH3 CH3-CH-CH3
CH3
Isomers (cont’d)2. Geometric Isomers: differ only in the geometry of their
substituted groups.
cis- 2 - butene trans- 2 - butene
cis-configuration: substituted groups are on the same side as the double bond.
trans-configuration: substituted groups are on the opposite sides of the double bond.
Warm-UpWork in pairs. You have 20 minutes to complete.
1. Draw the structural formulas: 3. Name the following:
a) 3-ethyl-1,4-cyclopentene
b) 1-chloro-2,3,4-triethyl-3-heptene C = C
c) 2-fluoro-7,7-dimethyl-4-decyne
2. Draw the cis and trans forms of the C = C
following alkenes:
a) 2-pentene 4. Identify the asymmetric
b) 2-octene carbon, if any:
c) 2-methyl-2-heptene a) CH3CH2CHO
d) 2,3-dimethyl-2-butene b) CH3CHOH
H
CH3 CH2CH2CH3
H
CH3
CH3 CH3
CH3
CH3
a)
b)
Isomers (cont’d)
Stereoisomers: molecules of the same molecular structure that
differ only in the arrangement of the atoms in space. They are
mirror images of each other (think right and left hands.)
Isomers (cont’d)
Stereoisomers: molecules of the same molecular structure that
differ only in the arrangement of the atoms in space. They are
mirror images of each other (think right and left hands.)
Left-handed (S)
Isomers (cont’d)
Stereoisomers: molecules of the same molecular structure that
differ only in the arrangement of the atoms in space. They are
mirror images of each other (think right and left hands.)
Left-handed (S) Right-handed (R)
Isomers (cont’d)
Stereoisomers: molecules of the same molecular structure that
differ only in the arrangement of the atoms in space. They are
mirror images of each other (think right and left hands.)
“left-handed” “right-handed”
Aromatic Hydrocarbons
Aromatic hydrocarbons are hydrocarbons that have six-membered
carbon rings and delocalized electrons. Benzene is the primary
aromatic hydrocarbon.
Benzene has the chemical formula C6H6 and can also be thought of
as 1,3,5-cyclohexatriene (hexene).
Benzene can also be represented graphically like this.
Isomers (cont’d)
Asymmetric Carbon: a carbon with four different groups attached to it.
C
F
Cl
BrH
Chlorofluorobromomethane
Functional Groups
• Besides our basic hydrocarbon classes, we can add other elements/ions, groups of elements to an organic structure = Functional Groups
• R = radical or, in this case, represents C• Alcohols (R-OH), ethers (R-O-R), carboxylic
acids (R-COOH), aldehydes (R-COH) – what are the others presented in the book?
• Identifying these!• Naming these (all have their own endings)!
Let’s practice drawing and naming!
Open text to p. _____
Classes of Organic Compounds
A functional group gives an organic compound properties that are very different from those of corresponding hydrocarbons.
Some examples:
1. Alcohols: are organic compounds that contain one or more hydroxyl groups. The general formula for alcohols is R-OH (rememeber that “R” stands for the rest of the
molecule.)
Glycerol: 1,2,3-propanetriol
Ethanol: 1-ethanol
Classes of Organic Compounds (ctn’d)
2. Ethers: are organic compounds in which two hydrocarbon
groups are bonded to the same oxygen atom. This can
can be represented by the formula R-O-R.
Diethyl Ether:
Dioxane:
Dimethyl Ether:
Classes of Organic Compounds (ctn’d)
3. Aldehydes and ketones: contain the carbonyl group:
Aldehyde: organic compound in which the carbonyl group is
attached to a carbon atom at the end of a carbon chain.
Ketone: organic compound in which the carbonyl group is
attached to carbon atoms within the chain.
Aldehyde Ketone
Classes of Organic Compounds (ctn’d)
4. Carboxylic Acids: are organic compounds that contain the
carboxyl functional group. A member of this class of organic
compounds can be represented by the general formula:
5. Esters: are organic compounds that have carboxylic acid groups
in which the hydrogen of the hydroxyl group has been replaced
by an alkyl group. Observe:
Classes of Organic Compounds (ctn’d)
Many esters have distinctive fruit-like odors, which has led to their
commonplace use in artificial flavorings and fragrances. Examples:
Let’s practice drawing and naming!
Open text to p. _____